When a metal layer contacts with a lightly doped semiconductor material, a contact effect comparable to a PN-junction diode appears. It is called the Schottky contact. This effect is used to make Schottky diode. When forward biased, a Schottky diode is in an “on” state and current flows through the diode. When the diode is reversely biased, a Schottky diode is in an “off” state and ideally current will not flow. Relative to other rectifier diodes, including PN-junction diode, the conventional Schottky diode exhibits high speed switching characteristics with very low forward conduction loss. Due to the combination of higher switching speeds and low forward conduction losses, Schottky diodes are commonly integrated as an internal diode within a semiconductor power device to function as a free-wheeling diode.
However, conventional Schottky diodes are not ideal. In reality, Schottky diodes experience an undesirable amount of reverse leakage current, which is detrimental to the performance of a circuit and results in a loss of power in the circuit. In addition, it is difficult to reliably enhance breakdown voltage of a Schottky diode without increasing forward conduction loss.
Accordingly, an improved Schottky diode for high-voltage applications with low reverse leakage current and high forward current drivability is desired.